Ring laser gyros are made of a ring laser gyro block with mirrors at the ends of the block. Legs exist in the ring laser gyro block to create a passageway between the mirrors which laser beams travel through for the operation of a ring laser gyro. To create the laser beams in the legs of the ring laser gyro, a current is supplied which is called the run current. The run current is supplied to anodes of the ring laser gyro and travel through portions of the legs to the cathode of the ring laser gyro. The run current is required for operation of the ring laser gyro in supplying adequate power for lasing in the legs of the ring laser gyro. Ring laser gyros currently operate at a fixed run current. The fixed run current level is determined by numerous factors, but is typically set at 2 to 5 times the lasing threshold in order to provide adequate laser power in the ring laser gyro.
The run current is set at a fixed level to ensure that adequate power exists for the ring laser gyro to operate in all temperature environments. The typical temperature range that a ring laser gyro operates in is 85 degrees Celsius to -40 degrees Celsius. At lower temperatures, a larger amount of current is required for operation since the laser intensity decreases as the temperature decreases. Therefore, the run current was fixed at a higher level to accommodate the low temperature range. Though the operation continued to be satisfactory at these lower cold temperatures, the run current was set at an unnecessarily higher level than required for the higher temperatures.
The operation of a ring laser gyro is above 4 degrees Celsius ninety percent of a ring laser gyro's lifetime. Therefore, power is wasted at most of the ring laser gyro's life. Further, in addition to the waste of power, a higher power supply decreases the life of elements within the ring laser gyro such as the mirrors and the cathode due to the higher energy source that degrades these elements. As a result, it would be beneficial if the run current was decreased for the majority of a ring laser gyro's lifetime so that the projected lifetime of the gyro would be increased due to longer life of the ring laser gyro elements such as the mirrors and the cathode. It would be beneficial if the capability existed to control the run current so that it was variable depending on the temperature range that the ring laser gyro operated at so that energy, materials and money could be saved.